In the patent US2008/0018325 titled “Apparatus and Method for Measuring an Output Power of a Power Supply”, a measuring apparatus comprised of a circuit board and a meter had been disclosed, which is used for measuring an output power of a power supply. The measuring apparatus disclosed in US2008/0018325 may be used for measuring a current, a voltage, and a power provided by the power supply to a motherboard, so as to instantly find out whether the actual requirements has been fulfilled by the power supply or not.
However, the measuring apparatus has the following disadvantages:    1. The circuit board still needs an additional meter for the measurement of voltage, currents, and power, which increases the overall size and measuring costs of the measuring apparatus.    2. In regard to each independent power source of the power supply (for example, 3V, 5V, and 12V), because each independent power source has to rely on two lead wires for connecting the circuit board to the meter. For instance, when three independent power sources including 3V, 5V, and 12V are used, six lead wires would be required for connection, which further complicates the connection of the lead wires.    3. The circuits between the circuit board, the meter, the power supply, and the motherboard can only be used for transmitting signals in one way, which is inconvenient to use.    4. The meter can only be used for collecting signals of voltage, currents, and power of the circuit board, and is not connected to the motherboard, thus cannot be used for collecting signals of the motherboard.
It is therefore tried by the inventor to develop a motherboard having a built-in system power management circuit to solve the problems existing in the measuring apparatus as described above.